consumer acceptability of a kombucha coffee (coffea)
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CONSUMER ACCEPTABILITY OF A KOMBUCHA COFFEE (COFFEA)
PROTOTYPE WITH TRADITIONAL COFFEE CHARACTERISTICS
A THESIS
Presented to the Department of Family and Consumer Sciences
California State University, Long Beach
In Partial Fulfillment
of the Requirements for the Degree
Master of Science in Nutritional Science
Committee Members:
Cheryl Rock, Ph.D. (Chair) Rachel Blaine, D.Sc. Christine Costa, DNP
College Designee:
Wendy Reiboldt, Ph.D
By Linh M. Le
B.S., 2015, California State University, Sacramento
August 2017
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ABSTRACT
CONSUMER ACCEPTABILITY OF A KOMBUCHA COFFEE (COFFEA)
PROTOTYPE WITH TRADITIONAL COFFEE CHARACTERISTICS
By
Linh M. Le
August 2017
Coffee and Kombucha tea are both beverages that have been consumed for many years,
with a current increased momentum in consumption due to many correlations with beneficial
health aspects. The objective of this study was to assess the consumer acceptability of a
Kombucha Coffee which tastes more like traditional coffee. A Kombucha Coffee prototype
“BubbLê,” was created and compared to a market Kombucha Coffee via a hedonics evaluation,
food action rating scale (FACT), and a paired-comparison ranking test. Participants rated the
market Kombucha Coffee significantly higher than BubbLê Kombucha Coffee in all sensory
aspects for flavor (6.84 ± 1.82; 4.46 ± 2.48; p < 0.001), sweetness (7.11 ± 1.63; 4.65 ± 2.33; p <
0.001), tartness (6.27 ± 1.77; 4.72 ± 2.55; p < 0.001), aroma (6.30 ± 1.82; 5.55 ± 2.59; p =
0.018), mouthfeel (6.87 ± 1.62; 5.36 ± 2.64; p < 0.001), and overall likeability (6.90 ±1.76; 4.59
± 2.43; p < 0.001) in the hedonics evaluation. The FACT test indicated that participants would
more likely drink the market alternative compared to the prototype (5.42 ± 1.96; 3.62 ± 2.29; p <
0.001). The majority of participants (80%) chose the market Kombucha Coffee over the more
traditional coffee flavored Kombucha Coffee prototype. It is noted that flavor scored the lowest
in sensory evaluation for the prototype, therefore, reevaluation of flavor by means of adding
coffee enhancing notes is needed for further development of a Kombucha Coffee with a more
traditional coffee flavor profile.
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ACKNOWLEDGEMENTS
This study could have not been fulfilled without the generous donations made by Temple
Coffee Roaster of Sacramento, California. I would also like to thank my committee members
Dr.Cheryl Rock, Dr.Rachel Blaine and Dr.Christine Costa for their continuous support and
guidance throughout the thesis process along with Dr.Wendy Reiboldt for her assistance with the
statistical analysis portion.
Finally, I would like to dedicate my work to my family and friends, especially my parents
who afforded me this amazing opportunity through the many sacrifices and hardships they have
endured.
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TABLE OF CONTENTS ABSTRACT………………………………………………………………………………………ii
ACKNOWLEDGEMENTS………………………………………………………………………iii
LIST OF TABLES………………………………………………………………………………...v
LIST OF FIGURES………………………………………………………………………………vi
1. INTRODUCTION……………………………………………………………………….....1
2. REVIEW OF LITERATURE………………………………………………………………7
3. METHODOLOGY…………………………………………………………...……….......21
APPENDICES…………………………………………………………………………………...26
A. FERMENTED COFFEE FORMULATION, FLOW CHART AND 5 D'S OF PRODUCT DEVELOPMENT…………....…………………………………………27
B. SENSORY EVALUATION FLYER………………………………………………...31
C. DEMOGRAPHIC QUESTIONNAIRE……………………………………………...33
D. INFORMED CONSENT FORM…………………………………………………….35
E. SENSORY EVALUATION SCORE CARDS………………………………………38
F. FACULTY SUPPORT LETTER…………………………………………………….42
G. DEPARTMENT PERMISSION LETTER………………………………………......45
H. MANUSCRIPT………………………………………………………………………47
REFERENCES…………………………………………………………………………………..66
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LIST OF TABLES
1. List of Gourmet Coffee Beverages………………………………………………………..8
2. Effects of Kombucha on the Lab Levels of Normal and Experimental Rats……..……...13
3. Comparison of Chlorogenic Acids (Caffeoylquinic Acid [CQA] Expressed in Mg/100 Ml) Extracted Via Espresso Versus Filter Method ………………………..….…………19
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LIST OF FIGURES
1. Coffee consumption and relationship to T2DM risk……………………..………….…..10
2. Coffee consumption and relationship to risk for heart failure….………………………..11
3. Kombucha fermentation…………………………………………………...……………..15
4. Antioxidant effect of cold versus hot tea, shown as the lag time, on LDL oxidation…....16
5. Structures of identified extracted coffee compounds………...……………………..……18
6. Encore 485 grinder set at 30 and coffee grounds………………………………………...21
7. Cold brew coffee before refrigeration……………………………………………………22
8. Chemex with metal mesh strainer…………………………………………………..……22
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CHAPTER 1
INTRODUCTION
Cardiovascular disease (CVD), cancer, and diabetes are among the leading causes of
human death in the United States with a total death rate of 1,282,535 in 2014 (Centers for
Disease Control and Prevention [CDC], 2015). Cardiovascular disease is an umbrella term for a
range of diseases the affect the heart and blood vessels (World Heart Federation, n.d.). Diabetes
is a type of disease in which the body is unable to use blood glucose for energy, resulting in
hyperglycemia (American Diabetes Association , 2014). Cancer is a term for diseases in which
abnormal cells divide without control which can invade other tissues leading to complications
(National Cancer Institute, n.d.). The World Health Organization (WHO), Food and Agriculture
Organization (FAO) and the CDC are in agreement that these various diseases can be prevented
with proper diet and lifestyle (CDC & U.S. Department of Health and Human Services, 2008;
WHO/FAO, 2002). Many of these diseases are thought to stem from free radicals and reactive
oxygen species (ROS), which compromise the human body’s cells and tissues (Lobo, Patil,
Phatak & Chandra, 2010). Both of these unstable and reactive compounds derive from normal
metabolic processes within the human body or from external sources such as exposure to X-rays,
ozone, cigarette smoking, air pollutants, and industrial chemicals (Bagchi & Puri, 1998). In low
concentrations, free radicals and ROS do have beneficial roles, such as human defense
mechanism of destroying invading pathogenic microbes (Dröge, 2002; Young & Woodside,
2001). In excessive amounts, free radicals and ROS in the human body lead to a phenomenon
known as oxidative stress which can dramatically alter cell membranes, resulting in the
development of those chronic and degenerative diseases such as cancer and CVD. The human
body defends itself against oxidative stress by utilizing antioxidants, which are known to combat
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against free radicals and ROS (Pham-Huy, He, & Pham-Huy, 2008).
Coffee consumption has been associated with the possibility of reducing the risks for
diseases, due to high amounts of dietary antioxidants present (Andersen, Jacobs, Carlsen, &
Blomhoff, 2006). Epidemiological studies suggest that coffee consumption is associated with the
prevention or delay of degenerative diseases, which include diabetes, CVD and cancer (Zhang,
Lopez-Garcia, Li, Hu, & Dam, 2009). Deoxyribonucleic acid (DNA) protective properties of
coffee reduce free radical and ROS cellular damage, which may be implicated in cancer
development (Bakuradze et al., 2011). These beneficial effects have been partly attributed to the
antioxidant activity present in coffee consumption (Hoelzl et al., 2010).
Coffee (coffea) is one of the most popular beverages consumed around the world with
increasing consumption of Gourmet Coffee Beverages (GCB). More than half of the American
adult population consumed this beverage daily in 2015 (National Coffee Association USA
[NCA], 2016b). A traditional cup of coffee is depicted by a flavor complexity of sensations
described as a combination of aroma, taste, texture and mouthfeel (Taylor & Roozen, 1996).
Among the sensations, aroma is notably the most important (Cliff & Green, 1994).
There is currently a trending increase in consumption of GCB, defined by the NCA
(2016a) as specialty coffee including gourmet traditional coffee, espresso-based beverages, along
with iced or frozen drinks. More specifically, gourmet coffee derives from premium grade coffee
beans of specific species, such as the Arabica, which are more scarce due to difficulty to grow in
specific geographical regions. In 2012, 44% of coffee consumers chose GCB over non-GCB,
which increased to 54% in 2014 (Murray, 2014). Within the GCB category, espresso-based
beverages also showed a steady increase in consumption. Espresso-based beverages are
variations of coffee drinks with at least one shot of espresso present. Of the GCB consumers,
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espresso-based beverages made up 35% of the consumption in 2012 and increased to 52% of the
GCB consumption in 2014 (Murray, 2014).
Similarly to coffee, another beverage that has many beneficial health properties is
Kombucha tea (KT). Kombucha tea is traditionally a sweetened black tea that is fermented with
a symbiotic culture of yeast and bacteria to produce a mild vinegar taste with an effervescent
finish (Marsh, O'sullivan, Hill, Ross,& Cotter, 2014; Watawana, Jayawardena, Gunawardhana,
& Waisundara, 2015). This tea has been brewed in China for over 2,000 years and has acted as a
functional beverage due to its ability to combat chronic illnesses such as CVD, cancer and type 2
diabetes (Marsh et al., 2014; Watawana et al., 2015).
There are many different techniques to produce brewed coffee with varying amounts of
antioxidants (Babova, Occhipinti, & Maffei, 2016; Lopez-Galilea, Peña, & Cid, 2007; Ludwig,
Bravo, Peña, & Cid, 2013; Yilmaz, Hacibekiroglu, & Kolak, 2014). These brewing techniques
can be generally characterized by brewing pressure, brewing process, extract volume, and solid
content (Parenti et al., 2014). The current brewing method that results in highest antioxidant
capacity when compared to other conventional brewing techniques is the espresso method,
obtained via percolation of hot water under pressure through compacted roasted ground coffee
(Illy & Viani, 2005; Lopez-Galilea et al., 2007; Ludwig et al., 2012). Another brewing technique
commonly used is cold brewing, which uses coarsely ground coffee mixed with cold water that is
left in a refrigerator for at least 12 hours (Perratore, 2016). This novel form of brewing coffee
can lead to potentially higher extract of antioxidant levels.
Justification of Study
Although there is a vast amount of research on both beverages, there is limited research
on the potential benefit of amalgamating the brewing and fermenting techniques of coffee and
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KT in order to create a highly nutrient dense functional beverage with traditional coffee
characteristics. These characteristics include the visual appearance of coffee along with taste.
Coffee’s appearance is characteristically marked by the rich dark brown color melanoidins
(Shibamoto, 1983). Traditional flavor and mouthfeel of coffee is depicted as sweet-caramel,
astringent, bitter flavor, earthy, roast/sulfur and smoky (Bicho, Leitão, Ramalho, de Alvarenga,
& Lidon, 2013; Czerny, Mayer & Grosch, 1999; Mayer, Czerny & Grosch, 2000). Lexicon on
the most important characteristic of coffee, the aroma, includes sweet aromatic, sour aromatic,
roasted, burnt/acrid, nutty, cocoa, musty/earthy, floral, fruity and pungent (Bhumiratana,
Adhikari, & Chambers, 2011).
Currently there are minimal commercial products of Kombucha Coffee, the only option
available does not contain the aforementioned traditional coffee characteristics. A food product,
which combines the brewing techniques of coffee and its traditional characteristics, with the
fermentation techniques of KT, can offer an attractive alternative to carbonated beverages with
the added health benefits of both coffee and KT. While further studies are needed to understand
if there is a synergistic effect of combining coffee and the techniques of fermenting KT, food
scientists along with nutritionists can still design products aimed to provide consumers with a
functional beverage to promote general health. Due to the long consumption history of both of
these beverages, there is a potential for long-term acceptance of this beverage.
Objectives of Study
The objective of this thesis is to evaluate the consumer acceptability and preference of a
Kombucha Coffee prototype (BubbLê) versus commercial type using:
1. Determine whether subjects prefer BubbLê to the market alternative using the Paired-
Comparison Test.
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2. Compare the consumer’s degree of likeability of BubbLê with the market alternative
using the Hedonics Preference Test.
3. Evaluate BubbLê’s acceptance by measuring the frequency of the consumers’ desire to
consume BubbLê using the Food Action Rating Scale (FACT).
Definitions of Terms
Antioxidant: Are man-made or natural substances that may prevent or delay some types
of cell damage (U.S. National Library of Medicine, MedlinePlus, 2016).
Cold brew: A coffee brew that uses more coarsely ground coffee and is mixed with cold
water and left to sit in a refrigerator or at room temperature for at least 12 hours (Perratore,
2016).
Espresso: A coffee brew that is obtained by percolation of hot water under pressure
through compacted roasted ground coffee (Illy & Viani, 2005).
Filter coffee: Method of brewing coffee with coffee grounds put in a paper filter and is
extracted with boiled water by conventional percolation coffee machine. The brew is dripped
into a heated pot within 2-3 minutes (Moeenfard, Rocha, & Alves, 2014).
Free radical: An unstable and highly reactive molecular species capable of independent
existence that contains an unpaired electron in an atomic orbital (Lobo et al., 2010).
Hedonic test: A 9 - point scale that is widely used for measuring food acceptability
(Peryam & Pilgrim, 1957).
Kombucha: A carbonated beverage obtained by the fermentation of sugared tea with a
symbiotic culture of acetic bacteria and fungi (Dufresne & Farnworth, 2000)
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Mocha: Method of brewing coffee using an aluminum pot with ground coffee placed in
filter cup, filled with water then heated until the water reservoir is empty (Moeenfard et al.,
2014).
Principle display panel (PDP): The visual appearance of a package, which is the part of a
label, that is most likely to be displayed, presented, shown, or examined under customary
conditions of display for retail sale (U.S. Food and Drug Administration, 2015).
Reactive oxygen species (ROS): These are chemical compounds, which donate oxygen to
other substances leading to instability (Lobo et al., 2010).
Limitations
The major limitation of this study is that the sensory evaluation used subjects recruited
from the student body and staff within the Family and Consumer Sciences (FCS) department at
California State University, Long Beach (CSULB); therefore the sample may not be an overall
representation of the target population. Novelty and taste of the fermented coffee product may
not be accepted which can result in lower scores during sensory evaluation. These limitations
may lead to bias in the outcome of the results.
Assumptions
This research assumes that the respondents will answer truthfully to sensory evaluation
tests. Other products offered during taste test will help in determination of acceptability of
prototype. Another assumption is the validity of tools used for sensory evaluations and
antioxidant assessment is accurate and will work. Also it is assumed that the combination of use
of cold brewing coffee technique and the fermentation process of KT will yield a highly nutrient
dense product. There is also an assumption that the product produced will always result in a
consistent product with same quality, freshness and flavor profile.
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CHAPTER 2
REVIEW OF LITERATURE
Coffee and Kombucha Tea
The consumption of coffee dates back to many centuries ago with a history that started in
Abyssinia and Arabia. It was used for years in the classical period of Arabian medicine before
the cultivation of the plant spread throughout the tropics (Ukers, 1922). The progression of
coffee cultivation dates back to 575 A.D., but this progression was slow until the 15th and 16th
centuries where the use of coffee grew in the Yemen district of Arabia, which led to the spread
of coffee cultivation around the globe (Ukers, 1922). This popular beverage is now consumed
daily by more than half of the adult population in the United States (NCA, 2016b).
Over the years, there has been a shift in coffee consumption among younger adults
choosing more GCBs (Table 1). According to the NCA’s (2016a) the National Coffee Drinking
Trends (NCDT) 2016 showed that over the last 8 years, daily consumption of espresso-based
beverages have nearly tripled since 2008. In 2008 GCB consumption among 18-24 year old
individuals was 13% whereas in 2016 at 36%, and among 25-39 year olds it was 19% in 2008
and at 41% in 2016. For espresso-based beverage consumption, there was an increase of 13% for
18-24 year olds and 21% increase for the 25-39 year olds from 2008 to 2016 (NCA, 2016a).
There were three new coffee beverages added to the GCB category: flat whites, cold brew and
iced coffee infused with nitrogen. Of the three newly added GCBs, cold brew had the highest
consumption with increased sales of 115% from the year 2014 to the year 2015 (NCA, 2016a;
Perratore, 2016).
Kombucha tea (KT) has been consumed around the world for many years with its origins
dating over 2,000 years ago in China (Marsh et al., 2014). It has been known by various names
TABLE 1. List of Gourmet Coffee Beverages Type Definition Traditional Coffee Traditional Coffee drunk hot or iced that is brewed from
premium whole bean or ground varieties Espresso-based beverages These beverages have at least one espresso shot mixed.
• cappuccino • espresso • latte • café mocha • macchiato • flat white • Americano
Iced/Frozen blended coffee These coffee beverages are blended with ice before consumption.
Cold brew coffee This coffee requires for the coffee grounds to be brewed in water without heat for a long period of time
Iced coffee infused with Nitrogen This is iced coffee that has been infused with nitrogen to create a carbonated coffee drink.
Note: Adapted from National Coffee Drinking Trends, by National Coffee Association. Copyright 2016.
throughout the world such as red tea fungus, Champignon de longue vie, Ling zhi, kocha kinoko,
Chainii grib, and Chainii kvass (Malbaša, Lončar, Vitas, & Čanadanović-Brunet, 2011). It was
discovered and used for a long time in China for detoxification and energizing properties (Roche,
1998). It was later used by doctor Kombu who brought the tea fungus to Japan to cure the
digestive problems of Japanese emperor, Inkyo (Jayabalan, Malbasa, Loncar, Vitas, &
Sathishkumar, 2014). The name “Kombucha” was derived from that physician’s name “Kombu”
with the Japanese word for tea, “cha,” to create the name of “Kombucha” (Roche, 1998).
Kombucha tea continued to make its way throughout the world surfacing in Russia where it was
also known by many other names such as Japonskigrib or Kambucha. It then made its way
through other eastern European countries, showing up in Germany in the 20th century, then in the
1950s KT arrived in France and its dominated regions of North Africa; this beverage continued
to increase in popularity during the 1960s after scientific research in Switzerland found that the
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benefits of consuming this beverage were similar to the consumption of yogurt (Jayabalan et al.,
2014). Kombucha tea is currently sold worldwide in various flavors and continues to build
popularity (Dufresne & Farnworth, 2000; Jayabalan et al., 2014).
However, with the changes and demands in food and beverage trends, (1) coffee and KT
consumption, due to their affiliated health benefits, has increased along with optimization of (2)
current brewing techniques, to (3) application of novel brewing techniques such as cold brewing
in new product development.
Coffee and Kombucha Tea Consumption and Their Health Benefits
Both coffee and KT have been consumed for long periods of time for their health
benefits. Coffee has been consumed for the caffeine content to enhance and stimulate focus and
energy, whereas KT has been consumed for centuries due to the testimonials and claimed health
benefits (Babova et al., 2016; Jayabalan et al., 2014). Much research has been conducted on both
of these beverages for the health effects they have on the human body. Kombucha tea and coffee
each have shown to have positive health benefits. Prospective studies have shown beneficial
health properties of coffee, as the consumption over time may decrease the risk for CVD and all
causes of mortality (Freedman, Park, Abnet, Hollenbeck, & Sinha, 2012; Sugiyama et al., 2010;
Zhang et al., 2009).
Coffee Consumption and Health Benefits
Recent studies have shown the potential health benefits of consuming coffee and its
relationship to leading causes of human death in America. These health benefits include but are
not limited to lowered risks for onset of various diseases such as heart disease and Type 2
diabetes mellitus (T2DM; Cano-Marquina, Tarin, & Cano, 2013; Harvard T.H. Chan School of
Public Health, 2010). Huxley and others (2009) further confirmed the relationship of coffee
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consumption and risk of development of T2DM, concluding that subjects who drank > 6 cups
daily had the lowest risk for T2DM (relative risk [RR]: 0.65; 95% CI: 0.54 to 0.78) while there
was also a significantly reduced risk in subjects who consumed 4 to 6 cups daily (RR: 0.72; 95%
CI: 0.62 to 0.83; Figure 1).
The relationship between coffee consumption and subsequent type 2 diabetes mellitus in different categories of coffee consumption. The center of each black square is placed at the summary point estimate; the area of the square is proportional to the statistical size; and each vertical line shows the 95% confidence interval about the summary estimate. FIGURE 1. Coffee consumption and relationship to T2DM risk. Adapted from “Coffee, Decaffeinated Coffee, and Tea Consumption in Relation to Incident Type 2 Diabetes Mellitus: A Systematic Review With Meta-Analysis,” by R. Huxley, C. Lee, F. Barzi, L. Timmermeister, S. Czernichow, E. Perkovic, … M. Woodward, 2009, Archives of Internal Medicine, 169, p. 2059. Copyright 2009.
In a 13 year follow-up of a prospective cohort research of 402,260 subjects, Freedman
and others (2012) showed an inverse association between consumption of coffee and many
leading causes of death, such as stroke, heart disease, and diabetes. As coffee intake increased
the risk for heart failure decreased until the threshold of more than 9 cups per day was reached
(Figure 2; Mostofsky, Rice, Levitan, & Mittleman, 2012). High blood pressure (BP), also known
as hypertension, is directly related to increasing the heart’s workload, leading to heart failure
(American Heart Association, 2016). One of coffee’s main constituents, caffeine, plays a
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hemodynamic role in lowering BP; caffeine has the ability to interfere with action of adenosine
on its receptors A1 (vasoconstrictor, increase BP) and A2a (vasodilator, decrease BP; Chrysant,
Relative risk (solid line) and 95% confidence interval (dashed lines) for the association between heart failure and cups of coffee per day compared with no consumption in a meta-analysis of studies published in 2001 to 2011. FIGURE 2. Coffee consumption and relationship to risk for heart failure. Adapted from “Habitual Coffee Consumption and Risk of Heart Failure Clinical Perspective: A Dose-Response Meta-Analysis,” by E. Mostofsky, M. Rice, E. Levitan & M, Mittleman, 2012, Circulation: Heart Failure, 5, p. 404. Copyright 2012. 2015). Caffeine acts as an inhibitor of A1 receptors for the afferent arteriole, glomerulus,
proximal tubule, and collecting ducts which improves glomerular filtration rate and renal blood
flow then causes diuresis and natriuresis, ultimately lowering the BP which has shown to
improve the condition of individuals with heart conditions (Cano-Marquina et al., 2013). In
addition to this inhibitory factor caused by caffeine and chlorogenic acids, they act as strong
antioxidants to improve endothelial and vascular function through increasing nitric oxide
(Guessous, Eap, & Bochud, 2014).
Another major health benefit of coffee is its ability to protect DNA from being damaged
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by decreasing spontaneous DNA breakage (Bakuradze et al., 2011, 2014). When observing the
relationship between coffee consumption and the levels of oxidative stress, there is also an
inverse relationship between coffee consumption and derivatives of reactive oxygen metabolites
(Ishizaka, Yamakado, Toda, Tani, & Ishizaka, 2013). These health benefits and associations of
coffee can be attributed to the antioxidants present in coffee, with its antioxidants showing high
potentials to act on free radicals and protect cells (Babova et al., 2016).
Kombucha Tea Consumption and Health Benefits
Kombucha tea has been an accepted beverage for centuries due to the many health
benefits with recent studies showing positive effects on diabetes. It has been reported that in
diabetic induced rats, KT was more beneficial than black tea at inhibiting α-amylase and lipase
activities in the plasma and pancreas while exuding higher suppression of increased blood
glucose levels (Aloulou et al., 2012). Additionally, Aloulou and others (2012) also found
ameliorative action of KT on the pancreas; moreover, the KT supplemented diabetic rats were
observed to have a significant decrease of 50 ± 11% in blood glucose concentration (p < 0.05).
Additionally, antihyperglycemic properties were shown with the continual consumption of 6
mg/kg body weight KT for 45 days in diabetic induced rats, resulting in a significant decrease in
blood glucose levels and glycosylated hemoglobin with increases in plasma insulin and tissue
glycogen (Table 2). Table 2 shows that the addition of KT can improve the glycemic state of
diabetic induced rats by bringing total hemoglobin and glycated hemoglobin to near normal
levels (12.01 +/- 0.84 g/dl; 0.27 +/- 0.03 mg/g Hb, respectively) of the control rats (Srihari,
Karthikesan, Ashokkumar, & Satyanarayana, 2013). Other researchers found that KT improved
serum glucose levels by 56.4% (p < 0.05) in diabetic induced rats compared to the control group
(Bhattacharya, Gachhui, & Sil, 2011.
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In addition to the health benefits shown in diabetes, KT has antioprolifeative activity on
cancer cells of the HeLa cells (cervix epithelial carcinoma), HT-29 (colon adenocarcinoma), and
MCF-7 (breast adenocarcinoma; Cetojevic-Simin, Bogdanovic, Cvetkovic, & Velicanski, 2008).
Prostate cancer cells significantly decreased in survival with the presence of KT extract due to
the downregulation of angiogenesis stimulators such as matrix metalloproteinase,
cyclooxygenase-2, interleukin-8, endothelial growth factor, and human inducible factor-1α
(Srihari, Arunkumar et al.,2013)
TABLE 2. Effects of Kombucha on the Lab Levels of Normal and Experimental Rats Groups Plasma Glucose
(Mg/Dl) Plasma Insulin (µu/Ml)
Total Hemoglobin (G/Dl)
Glycated Hemoglobin (Mg/G Hb)
Normal 92.67 ± 7.23a 12.82 ± 1.02a 12.01 ± 0.84a 0.27 ± 0.03a
Normal + Kombucha (12 mg/kg)
93.78 ± 8.64a 11.96 ± 0.98a 12.58 ± 0.92a 0.26 ± 0.02a
Diabetic 278.36 ± 25.72b 3.92 ± 0.31b 8.02 ± 0.59b 0.74 ± 0.06b
Diabetic + Kombucha (3 mg/kg)
222.33 ± 20.18c 5.97 ± 0.46c 8.88 ± 0.48c 0.62 ± 0.05c
Diabetic + Kombucha (6 mg/kg)
120.01 ± 10.86d 9.22 ± 0.64d 10.58 ± 0.98d 0.36 ± 0.03d
Diabetic + Kombucha (12 mg/kg)
163.31 ± 14.84e 7.18 ± 0.53e 9.42 ± 0.38e 0.56 ± 0.05e
Values in each group are represented as means ± S.D. for 6 rats in each group. Values not sharing a common superscript a–e differ significantly at p < 0.05. Note: Adapted from “Antihyperglycaemic Efficacy of Kombucha in Streptozotocin-Induced Rats,” by T. Srihari, K. Karthikesan, N. Ashokkumar, and U. Satyanarayana, 2013, Journal of Functional Foods,5, p. 1799. Copyright 2013.
Current Brewing Techniques for Coffee and Kombucha Tea
Production of Coffee and Kombucha Tea
There are many different techniques used to produce brewed coffee and tea. The brewing
of coffee can be generally characterized by the brewing pressure, brewing process, brew volume,
14
and solid content (Parenti et al., 2014). The most conventional products of coffee brewing are:
filtered coffee, espresso, and cold brew (Illy & Viani, 2005; Moeenfard et al., 2014; Perratore,
2016). These various brewing techniques widely affect the flavor profile and chemical
compounds of coffee (Babova et al., 2016). Similarly to coffee, there are various ways to brew
tea (Jayabalan et al., 2014). After the tea is brewed, additional steps of fermentation are needed
to produce KT, which will be discussed in detail in the review of literature that follows.
Conventional Methods of Brewing Coffee
There are multiple ways to conventionally brew coffee for consumption, which includes
filtration, espresso and full immersion. The most common and conventional form of coffee
brewing is the use of the filter coffee technique. This is a method of brewing in which coffee
grounds are placed in a paper filter then boiled water percolates into a coffee machine and then is
dripped into a heated pot (Moeenfard et al., 2014). Second, another conventional form of
brewing is espresso ; this method is done via percolation of hot water under pressure through
compacted roasted ground coffee (Illy & Viani, 2005). Other methods used for brewing coffee
are the following: boiling; French pressing, and cold brewing, all of which require complete
submersion of the grounds in hot or cold water for an extended period of time until the liqueur
(i.e., brew) is separated from the solids (Moeenfard et al., 2014; Perratore, 2016). Cold brewing
is a novel technique of brewing coffee, which requires the use of more coarsely ground beans,
mixed with cold water and left in a refrigerator for at least 12 hours to slowly extract the plant
solubles (Perratore, 2016).
Conventional Brewing of Kombucha Tea
The traditional preparation of KT consists of three basic ingredients which are: brewed
tea, sugar and the symbiotic culture of acetic acid bacteria and various species of yeast
15
(Jayabalan et al., 2014; Liu, Hsu, Lee, & Liao, 1996). The production of carbonated KT requires
two-step process of tea fermentation at between 20°C - 30°C (Figure 3). In the first step, KT is
prepared under aerobic conditions in which the yeast cells hydrolyze sucrose (C12H22O11) into
FIGURE 3. Kombucha fermentation. Photo courtesy of Linh Le. Copyright 2017.
glucose (C6H12O6) and fructose (C6H12O6; Reiss, 1994; Sievers, Lanini, Weber, Schuler-Schmid,
& Teuber, 1995). The acetic acid bacterium converts those substrates into gluconic acid
(C6H12O7) and acetic acid (C2H4O2; Balentine, Wiseman, & Bouwens, 1997). The presence of
acetic acid creates a cyclic affect, which stimulates the yeast to produce ethanol (C2H6O), and the
alcohol then aids in the growth of acetic acid bacterium, which then produces more of itself (Liu
et al., 1996). The end product results in total consumption of sucrose after 2 weeks of
fermentation with the production of ethanol, acetate and a Kombucha cellulose pellicle (Kallel,
Desseaux, Hamdi, Stocker, & Ajandouz, 2012). The second step of fermentation involves the
development of naturally occurring carbon dioxide (CO2), which occurs in an anaerobic
16
environment in which the yeast continues to ferment the sugars resulting in a carbonated
beverage (Chen & Lui, 2000).
Cold Brewing Coffee and Tea
Cold brewing is an emerging technique used to brew coffee or tea in cold water for a
prolonged period of time which can lead to enhanced product yield. When this procedure is
applied in tea brewing (room temperature [25°C ] for 2 hours), higher antioxidant activity is
observed in cold brew teas compared to hot brewed teas (Figure 4), with white tea having the
ability to more than double the lag time of copper-induced low density lipoprotein (LDL)
oxidation compared to the control (Venditti et al., 2010). The conditions for this system under
which coffee is brewed is as follows: 3.3°C for at least 12-18 hours (Perratore, 2016). The
soluble solids present in coffee grounds decrease in extractability as the temperature of the
solvent decreases, therefore, requiring longer brewing times for this method (Strumpf, 2015).
FIGURE 4. Antioxidant effect of cold versus hot tea, shown as the lag time, on LDL oxidation. Adapted from “Hot Vs. Cold Water Steeping of Different Teas: Do They Affect Antioxidant Activity?” E. Venditti, T. Bacchetti, L. Tiano, P. Carloni, L. Greci, and E. Damiani, 2010, Food Chemistry, 119, p. 1601. Copyright 2010.
17
Cold brewing can offer a better extraction of active components and results in a unique flavor
profile that is less acidic and bitter compared to its counterparts (Phung, 2014; Wang, Xu, Feng,
Yang, & Qian, 2011).
Brewing Effects on Antioxidants Extracted from Coffee
Among the various coffee brewing techniques, studies have shown that levels of
antioxidants can vary depending on the coffee brewing method used. In addition to the
commonly known compound found in coffee, caffeine, there are also abundant amounts of
beneficial health components such as phenolic compounds, tocopherols, neochlorogenic acids
and chlorogenic acids (Figure 5), within this beverage that play a role in antioxidant activity and
human health (Babova et al., 2016; Herman & Herman, 2013). In a study led by Lopez-Galilea
and others (2007), espresso showed to have the highest antioxidant capacity when compared to
other brewing techniques of filter, mocha and plunger: (espresso > mocha > plunger > filter).
Furthermore, other studies also show espresso coffee being superior in obtaining chlorogenic
acids compared to that of the filter coffee brewing method. For example when looking
specifically at 5-caffeoylquinic acid the concentrations in espresso was 201.1 ± 1.6 mg/100 mL
where as in filter coffee it was 70.1 ± 0.3 mg/100 mL. Table 3 shows the differences in
chlorogenic acids extracted (Ludwig et al., 2012). ). Optimum tocopherol extraction from coffee
beans depends on the pressure that exists at the beginning of the extraction phase present in the
espresso extraction phase (Alves, Casal, & Oliveira, 2010).
New Developments in Product Development
Beverage Trends - Kombucha
The consumption of KT has increased over the last several years. In the 2016
Foodservice Trends and Carbonated Soft Drinks US 2015 reported that 51% of U.S. adults
18
(1) Caffeic acid, (2) p-coumaroylquinic acid, (3) p-coumaroyl-Ntryptophan, (4) chlorogenic acid (3-O-caffeoylquin-ic acid), (5) neochlorogenic acid (5-O-caffeoylquinic acid), (6) cryptochlorogenic acid (4-O-caffeoylquinic acid), (7) caffeoyl-N-tryptophan, (8) 3-O feruloylquinic acid,(9) 5-O-feruloylquinic acid, (10) 3,4-O-dicaffeoylquinic acid, (11) 3,5-O-dicaffeoylquinic acid, (12) 4,5-O-dicaffeoylquinic acid, (13) 3-O-feruloyl-4-caffeoylquinic acid, (14) 3-O-feruloyl-5-caffeoylquinic acid,(15) 4-O-feruloyl-5- caffeoylquinic acid, and (16) caffeine. FIGURE 5. Structures of identified extracted coffee compounds. Adapted from “Chemical Partitioning and Antioxidant Capacity of Green Coffee (Coffea Arabica and Coffea Canephora) of Different Geographical Origin,” by O. Babova, A. Occhipinti, and M. Maffei, 2016, Phytochemistry, 123, p.35. Copyright 2016.
19
between the ages of 25-34 already consumed the KT beverage (Menayang, 2016). There is
increased consumer interest in KT, which has forced retailers to stock their shelves with a variety
of KT products. Sales from one company (KeVita) alone surged by 6,682% from January of
2015 compared to January of 2016 (Crawford, 2016). There has been an increase in sales for
kombucha and fermented beverages by 32% since October 2015 to October 2016 (Watson,
2016). The kombucha market is predicted to have a large growth rate of 25% each year until the
year 2020 (Conick, 2016; Markets and Markets, 2015).
TABLE 3. Comparison of Chlorogenic Acids (Caffeoylquinic Acid [CQA] Expressed in Mg/100 Ml) Extracted Via Espresso Versus Filter Method Method 3-CQA 4-CQA 5-CQA 3,4-diCQA 3,5-diCQA 4,5-diCQA Espresso 91.3±1.3 114.6±0.6 201.1±1.6 9.8±0.2 4.2±0.1 9.6±0.4 Filter 31.0±0.3 40.9±0.1 70.1±0.3 6.1±0.3 2.9±0.1 6.0±0.0 Note: Adapted from “Extraction of Coffee Antioxidants: Impact of Brewing Time and Method,” by I. Ludwig, L. Sanchez, B. Caemmerer, L. Kroh, M. Peña, and C. Cid, 2012, Food Research International, 48, pp.62-63. Copyright 2012. Cold Brew Coffee Cold brew coffee is an emerging new technique in the brewing coffee industry that has
gained momentum in popularity. The NCA has added cold brew to the GCB category in 2016
(2016a). In 2015, the coffee trends report showed that 15% of coffee drinkers tried
cold brew coffee. There was an estimated 115% growth in sales for cold brew in 2015 (NCA,
2016b). Researchers also found that 37% of U.S. consumers between the ages of 29-38 years old
have an interest in cold brew coffee because they enjoy trying new styles of coffee preparation
(Sisel, 2015). The continuation of brewing novelty will increase sales of this brewed coffee over
the next several years.
Beverage Trends in New Food Product Development: Kombucha Coffee
Coffee and KT have both shown an enormous growth in popularity over the years, but
20
there is still a need to produce a high quality product that combines the potential health benefits
of both products. In the United States, it was reported that 42% of the consumers would like to
see added nutritional benefits of coffee consumption with possibly the addition of probiotics
(Sisel, 2015). A fermented coffee using the techniques of kombucha brewing has produced
naturally occurring probiotic rich beverage which can produce a functional beverage that will
satisfy consumer’s need for increased functional coffee beverages. Although, consumers can find
Kombucha Coffee in the local health food stores, the options are limited to one commercial
brand which uses the inferior antioxidant and flavor extraction method of filter coffee brewing.
With the rising popularity of cold brew coffee, a Kombucha Coffee using the cold water brewing
method can offer more high quality options for consumers. The main limitation of traditional
cold brewing is the long process needed to yield the coffee product.
Summary
As discussed, both KT and coffee consumption have several health beneficial aspects and
have been accepted for long periods of time. These health benefits of the two beverages include a
wide range of DNA protective properties along with heart disease prevention, antihyperglycemic
effects in diabetics, cancer cell degradation and organ restorative aspects. The techniques of
brewing these beverages widely affect the antioxidant profile extracted, which can disrupt those
beneficial health properties. The non-thermal and effective way of brewing coffee to preserve
those health properties can be attained with the use of cold brewing. With the aging of
millennials, there has been a shift in consumption of the two beverages which has proven to have
increased in demand (Menayang, 2016; NCA, 2016b). The need to use novel techniques like the
application of cold brewing with Kombucha fermentation to obtain these beverages will keep the
interest of millennials (Sisel, 2015).
21
CHAPTER 3
METHODOLOGY
Coffee Brewing Techniques
The brewing of coffee using cold methods was performed according to procedure of
Temple Coffee Roasters. In preparation of the coffee brew, high quality coffee beans (donated
from Temple Coffee Roasters, Sacramento, CA, USA) were used. Each coffee brewing
technique was conducted in triplicates and stored in the refrigerator until analysis.
Cold Brewing
Five-hundred grams of coffee was coarsely ground using a Baratza Encore 485 Coffee
Grinder set at the 27-grind setting (Figure 6). The ground coffee was immersed in 4,000 mL of
cold water, then placed in a refrigerator set at 3.3°C (38°F) for 18 hours (Figure 7). The brewed
coffee was filtered from the coffee grounds with a metal mesh strainer placed in a Chemex
(Figure 8). The process was repeated two more times.
FIGURE 6. Encore 485 grinder set at 30 and coffee grounds. Photo courtesy of Linh Le. Copyright 2017.
22
FIGURE 7. Cold brew coffee before refrigeration. Photo courtesy of Linh Le. Copyright 2017.
FIGURE 8. Chemex with metal mesh strainer. Photo courtesy of Linh Le. Copyright 2017.
23
Fermented Coffee Formulation
The fermented coffee formulation was produced in similar conditions as described by
Marsh and others (2014), with the exception of coffee being used in place of tea. A Kombucha
cellulose pellicle starter Kombucha culture was used. The coffee was brewed and weighed for
determination of sugar (10%). Fermentable sugar was determined by multiplying total brewed
coffee by 10% and divided in half for first and second ferment. The sugar was dissolved in
500mL of hot water and cooled then added to the brewed coffee in a sterile glass container
(Ball® Mason Jar). The Kombucha cellulose pellicle was added to the coffee solution (Figure 3).
The container was covered with a 100% cotton towel and an elastic band was fixed on. The
coffee mixture and Kombucha cellulose was placed in a dark space at room temperature (~23
°C) and fermented for 5 days. The second half of sugar was dissolved in 500mL of hot water and
cooled then added to the fermented coffee to be bottled in airtight 16 oz bottles for second
fermentation of 14 more days. After the second fermentation the developed BubbLê product was
refrigerated at 4°C until sensory analysis is performed.
Subject Recruitment, Evaluation, and Consumer Acceptability
The consumer acceptability study was submitted and accepted by the Institutional
Review Board (IRB) at California State University, Long Beach (CSULB). Consumer testing
was conducted in the sensory evaluation laboratory at the CSULB Department of Family and
Consumer Sciences (FCS) building. The sensory evaluation testing was performed under
controlled conditions—isolated booths, controlled lighting and temperature. Ninety untrained
subjects were recruited by flyers and advertisements (Appendix B). Subjects may have mainly
consist of staff and students from CSULB. Subjects were required to complete a questionnaire
that requested demographic information (age, gender, ethnicity) along with shopping habits prior
24
to the testing (Appendix C). Subjects in this study were excluded if they: (1) had a food allergy
to any of the products tested, (2) did not consume Kombucha or coffee products used in the study
for dietary or cultural reasons, and (3) had any professional experience in sensory evaluation.
The subjects were free to withdraw from the study without any consequences. Subjects were
required to sign an informed consent form and were compensated for their participation in this
study (Appendix D). Consumer acceptance was determined using three tests: (1) Ranking Tests,
(2) 9-point Hedonic Scale, (3) Food Action Rating Scale (FACT) test.
Objective 1: Paired-Comparison and Ranking Testing
Consumer preference of the prototype was evaluated using a Paired-Comparison Ranking
test using consumer panelists. The panel was provided with randomly coded 1 oz. samples of the
prototype (Code 604) and a market alternative (Code 247) in 2 oz., clear, plastic cups. The
subjects were instructed to enter the sample code they prefer most (Appendix E1). Water and
unsalted crackers were supplied to cleanse the palate between samples. The utilization of these
measures will provide the statistical data necessary to evaluate the prototype based on individual
consumer preferences, as well as analytic measurements to understand how consumers feel the
new prototype compares to the market alternative.
Objective 2: Hedonic Testing
Subjects were administered a 9-point hedonic scale for sensory evaluation where: (9 =
“like extremely”; 8 = “like very much”; 7 = “like moderately”; 6 = “like slightly”; 5 = “neither
like nor dislike”; 4 = “dislike slightly”; 3 = “dislike moderately”; 2 = “dislike very much”; 1 =
“dislike extremely”) to rate the prototype for attributes such as flavor, sweetness, tartness, aroma,
mouthfeel, and overall preference (Appendix E2). Panelists were provided with two randomly
coded samples of the fermented coffee prototype and a control sample (i.e., commercial brand).
25
The samples were distributed in 2 oz. clear plastic cups. Samples will also be administered
randomly to avoid bias. Water and unsalted crackers were supplied to the panelists to cleanse
their palate between samples.
Objective 3: The Food Action Rating Scale (FACT) Test
The FACT test will measure the fermented coffee prototype for the incidences of
drinking measurement as described by Ramcharitar and others (2005). A 9-point scale were used
and is as follows: 9 = “I would drink this every opportunity I had”; 8 = “I would drink this very
often”; 7 = “I would frequently drink this”; 6 = “I like this and would drink it now and then”; 5 =
“I would drink this if available but would not go out of my way”; 4 = “I do not like this but
would drink this on occasion”; 3 = “I would hardly ever drink this”; 2 = “I would drink this if
there were no other beverage choices”; 1 = “I would drink this only if forced”. Additionally,
subjects were asked how much they would be willing to pay for the product (Appendix E3).
Statistical Analysis
Descriptive statistics, including frequencies, percentages, and variance, were calculated
for scorecard ratings. Means, standard deviations (SD), and standard errors mean (SEM) were
calculated for each of the sensory attributes and Hedonic rating scores. Overall acceptability and
Hedonic ratings for the Kombucha Coffee prototype were tested using paired t-tests, via the
International Business Machine Statistical Package for Social Sciences (IBM SPSS) Statistics 22
for Windows. Correlations between overall acceptability and other sensory attributes were
computed, and coefficients of determination were reported. All analysis tests were performed
using a significance of at least p < 0.05.
26
APPENDICES
27
APPENDIX A
FERMENTED COFFEE FORMULATION, FLOW CHART AND 5 D'S OF PRODUCT
DEVELOPMENT
28
Appendix A1: Fermented Coffee Formulation
Fermented Coffee Formulation
Formulation to yield 3350mL Fermented Coffee Ingredient Grams Percent of
total formulation
Functionality
Kombucha Starter Culture
335 10% Inoculation of kombucha bacterium into product and acidify
Extracted Coffee 1340 40% Provides caffeine for production of kombucha
Boiling Water 1340 40% Sweetener solvent Organic Raw Cane Sugar
335 10% Sugar needed to promote bacterium growth and fermentation
Kombucha cellulose pellicle
70 N/A Culture byproduct of kombucha (scoby)
29
Appendix A2: Process Flow Diagram of Fermented Coffee
Process Flow Diagram of Fermented Coffee
Refrigerate
Allow for a 2nd derment at room temp for 7 days
Bottle into airtight bottles
Allow to ferment at room temp for up to 7 days
Add Kombucha celluolose pellicle and fasten cloth on top
Combine coffee and sugar solution in sterile glass
Dissolve sugar in water
Extract coffee at 3.3°C
Grind coffee
Purchase ingredients
30
Appendix A3: 5 D's of product Development
5 D's of product Development Stage Explanation Things to Think About Decide Fermented coffee
Brainstorming of ideas and what product to create, what’s needed and its concept
What is currently in the market? Do consumers need or want this product? What are the current health trends?
Discover Antioxidant Capacity
High cases of CVD among other leading causes of death which determines a need for higher antioxidant rich foods.
Target audience Age Gender Geographical location
Define Coffee and Kombucha consumers. Health conscious
Formulation ad packaging of fermented coffee.
Materials Ingredients Techniques to make kombucha
Develop Product will be a healthy Fermented coffee Product called BubbLê
Assemble a fermented coffee prototype with the packaging design, sensory analysis and product.
Type of packaging Label Graphic design
Deploy The product goes into the market.
Create a marketing plan. Decide on pricing, storage, promotion and advertising.
Social media Coffee shop partnerships Retailers
31
APPENDIX B
SENSORY EVALUATION FLYER
32
33
APPENDIX C
DEMOGRAPHIC QUESTIONNAIRE
34
35
APPENDIX D
INFORMED CONSENT FORM
36
CONSUMER ACCEPTABILITY OF A KOMBUCHA COFFEE (COFFEA)
PROTOTYPE WITH TRADITIONAL COFFEE CHARACTERISTICS
You are asked to participate in a research study conducted by Linh Le, from the Department of Family and Consumer Sciences at California State University, Long Beach. The results of this study will be contributed to my thesis for Master of Science in Nutritional Science. You were selected as a possible participant in this study because you are the at least 18 years of age and a student, faculty or staff enrolled or working at California State University, Long Beach. PURPOSE OF THE STUDY The overall objective of this study is to evaluate to evaluate the consumer acceptance of the BubbLêcoffee prototype produced using a novel technology and compared to traditional brewing techniques such as cold and hot brewing. PROCEDURES If you volunteer to participate in this study, you will do the following steps:
Step 1). Complete a demographic questionnaire Step 2). Participate in a sensory evaluation study in which you will:
a. Choose between a commercial brand of fermented coffee versus the fermented coffee prototype in a paired-comparison ranking test on various attributes.
b. Rate fermented coffee prototype on a hedonic rating scale about whether you like the product on certain attributes
c. Rate a fermented coffee for the incidence of eating measurement. d. Rank principle display panels of the fermented coffee prototype based on
preference.
The testing will be conducted in the sensory evaluation lab in the FCS department in room 112B. Water will be available throughout the study to cleanse your palate as needed. Testing will take about 7-15 minutes, depending on the amount of time you need to sample the product and evaluate. Once you have completed all of the tests, you will submit the questionnaire to the researcher and are free to leave. POTENTIAL RISKS AND DISCOMFORTS Potential risks and discomforts include consumption of a fermented product, which may cause gastric upset. Panelists are free to withdraw from the study at any point. The Student Health Center number (562) 985-4771) will be provided to participants if requested. POTENTIAL BENEFITS TO SUBJECTS AND/OR TO SOCIETY As a participant in this study you will gain formal training experience as a sensory food panelist. Additionally, you will get to try a new coffee beverage.
37
Potential benefits to this study include introduction of a functional beverage with high antioxidants and various health benefits. Such a product may be beneficial to the promotion of general health in the general population. PAYMENT FOR PARTICIPATION Participants will receive compensation in the form of a gift card (value of $5.00) for participation in this study. Compensation will be provided as you exit the testing room. Compensation will not be provided if you quit the study. CONFIDENTIALITY Any information that is obtained in connection with this study and that can be identified with you will remain confidential and will be disclosed only with your permission or as required by law. PARTICIPATION AND WITHDRAWAL You can choose whether to be in this study or not. In order to avoid a potential sense of coercion, if you volunteer to be in this study, you may withdraw at any time. Participation or non-participation will not affect you or any other personal consideration or right you usually expect. You may also refuse to answer any questions you do not want to answer and still remain in the study. The investigator may withdraw you from this research if circumstances arise which in the opinion of the researcher warrant doing so. IDENTIFICATION OF INVESTIGATORS If you have any questions or concerns about the research, please feel free to contact the principal Investigator, Linh Le at lmyle13@gmail.com or the research advisor, Dr. Cheryl Rock at cheryl.rock@csulb.edu RIGHTS OF RESEARCH SUBJECTS You may withdraw your consent at any time and discontinue participation without penalty. You are not waiving any legal claims, rights or remedies because of your participation in this research study. If you have questions regarding your rights as a research subject, contact the Office of University Research, CSU Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840; Telephone: (562) 985-5314. Email: ORSP-Compliance@csulb.edu SIGNATURE OF RESEARCH SUBJECT OR LEGAL REPRESENTATIVE I understand the procedures and conditions of my participation described above. My questions have been answered to my satisfaction, and I agree to participate in this study. I have been given a copy of this form. _________________________________________________ Printed Name of Subject __________________________________________________ ____________ Signature of Subject Date
38
APPENDIX E
SENSORY EVALUATION SCORE CARDS
39
Appendix E1: Paired-Comparison Score Card: Product Ranking
40
Appendix E2: Hedonic Rating Score Card
41
Appendix E3: Food Action Rating Scale (FACT) Score Card
42
APPENDIX F
FACULTY SUPPORT LETTER
43
44
45
APPENDIX G
DEPARTMENT PERMISSION LETTER
46
47
APPENDIX H
MANUSCRIPT
48
RESULTS AND DISCUSSION
CONSUMER ACCEPTABILITY OF A KOMBUCHA COFFEE (COFFEA)
PROTOTYPE WITH TRADITIONAL COFFEE CHARACTERISTICS
Linh Le1, Cheryl Rock1, Rachel Blaine1, Christine Costa2 and Wendy Reiboldt1
1Department of Family and Consumer Sciences. California State University, Long Beach, 90840
2Department of Nursing, California State University, Long Beach, 90840
Contact information for Corresponding Author
Dr. Cheryl Rock, 1250 Bellflower Boulevard, Long Beach, CA 90840, telephone: (562) 985-
4497, fax: (562) 985-4414, cheryl.rock@csulb.edu
Word count: 4101
Short version of title: Kombucha Coffee and Product Development
Choice of journal/section: Sensory and Food Quality
49
Abstract:
Coffee and Kombucha tea are both beverages that have been consumed for many years,
with a current increased momentum in consumption due to many correlations with beneficial
health aspects. The objective of this study was to assess the consumer acceptability of a
Kombucha Coffee which tastes more like traditional coffee. A Kombucha Coffee prototype
BubbLê, was created and compared to a market Kombucha Coffee via a hedonics evaluation,
food action rating scale (FACT), and a paired-comparison ranking test. Participants rated the
market Kombucha Coffee significantly higher than BubbLê Kombucha Coffee in all sensory
aspects for flavor (6.84±1.82; 4.46±2.48; p<0.001), sweetness (7.11±1.63; 4.65±2.33; p<0.001),
tartness (6.27±1.77; 4.72±2.55; p<0.001), aroma (6.30±1.82; 5.55±2.59; p=0.018), mouthfeel
(6.87±1.62; 5.36±2.64; p<0.001), and overall likeability (6.90±1.76; 4.59±2.43; p<0.001) in the
hedonics evaluation. The FACT test indicated that participants would more likely drink the
market alternative compared to the prototype (5.42±1.96; 3.62±2.29; p<0.001). The majority of
participants (80%) chose the market Kombucha Coffee over the more traditional coffee flavored
Kombucha Coffee prototype. It is noted that flavor scored the lowest in sensory evaluation for
the prototype, therefore, reevaluation of flavor by means of adding coffee enhancing notes are
needed for further development of a Kombucha Coffee with a more traditional coffee flavor
profile.
Key words: coffee, kombucha, product development, antioxidants, nutrition, health
50
Practical Application: Coffee and Kombucha tea can be regarded as functional beverages that
can promote overall health. Developing products which include traditional coffee flavors with
the fermentation techniques of Kombucha tea can lead to increased consumption of this high
antioxidant beverage leading to decreased cardiovascular disease, diabetes and cancers.
INTRODUCTION
Cardiovascular disease (CVD), cancer, and diabetes are among the leading causes of
human death in the United States with a total death rate of 1,282,535 in 2014 (Centers for
Disease Control and Prevention [CDC], 2015). Cardiovascular disease is an umbrella term for a
range of diseases the affect the heart and blood vessels (World Heart Federation, n.d.). Diabetes
is a type of disease in which the body is unable to use blood glucose for energy, resulting in
hyperglycemia (American Diabetes Association , 2014). Cancer is a term for diseases in which
abnormal cells divide without control which can invade other tissues leading to complications
(National Cancer Institute, n.d.). The World Health Organization (WHO), Food and Agriculture
Organization (FAO) and the CDC are in agreement that these various diseases can be prevented
with proper diet and lifestyle (CDC and U.S. Department of Health and Human Services, 2008;
WHO, 2002). Many of these diseases are thought to stem from free radicals and reactive oxygen
species (ROS), which compromise the human body’s cells and tissues (Lobo, Patil, Phatak &
Chandra, 2010). Both of these unstable and reactive compounds derive from normal metabolic
processes within the human body or from external sources such as exposure to X-rays, ozone,
cigarette smoking, air pollutants, and industrial chemicals (Bagchi & Puri, 1998). In low
concentrations, free radicals and ROS do have beneficial roles, such as human defense
mechanism of destroying invading pathogenic microbes (Dröge, 2002; Young & Woodside,
2001). In excessive amounts, free radicals and ROS in the human body lead to a phenomenon
51
known as oxidative stress which can dramatically alter cell membranes, resulting in the
development of those chronic and degenerative diseases such as cancer and CVD. The human
body defends itself against oxidative stress by utilizing antioxidants, which are known to combat
against free radicals and ROS (Pham-Huy, He, & Pham-Huy, 2008).
Coffee consumption has been associated with the possibility of reducing the risks for
diseases, due to high amounts of dietary antioxidants present (Andersen, Jacobs, Carlsen, &
Blomhoff, 2006). Epidemiological studies suggest that coffee consumption is associated with the
prevention or delay of degenerative diseases, which include diabetes, CVD and cancer (Zhang,
Lopez-Garcia, Li, Hu, & Dam, 2009). Deoxyribonucleic acid (DNA) protective properties of
coffee reduce free radical and ROS cellular damage, which may be implicated in cancer
development (Bakuradze et al., 2011). These beneficial effects have been partly attributed to the
antioxidant activity present in coffee consumption (Hoelzl et al., 2010).
Coffee (coffea) is one of the most popular beverages consumed around the world with
increasing consumption of Gourmet Coffee Beverages (GCB). More than half of the American
adult population consumed this beverage daily in 2015 (National Coffee Association USA
[NCA], 2016). A traditional cup of coffee is depicted by a flavor complexity of sensations
described as a combination of aroma, taste, texture and mouthfeel (Taylor & Roozen, 1996).
Among the sensations, aroma is notably the most important (Cliff & Green, 1994).
There is currently a trending increase in consumption of GCB, defined by the NCA
(2016a) as specialty coffee including gourmet traditional coffee, espresso-based beverages, along
with iced or frozen drinks. More specifically, gourmet coffee derives from premium grade coffee
beans of specific species, such as the Arabica, which are more scarce due to difficulty to grow in
specific geographical regions. In 2012, 44% of coffee consumers chose GCB over non-GCB,
52
which increased to 54% in 2014 (Murray, 2014). Within the GCB category, espresso-based
beverages also showed a steady increase in consumption. Espresso-based beverages are
variations of coffee drinks with at least one shot of espresso present. Of the GCB consumers,
espresso-based beverages made up 35% of the consumption in 2012 and increased to 52% of the
GCB consumption in 2014 (Murray, 2014).
Similarly to coffee, another beverage that has many beneficial health properties is
Kombucha tea (KT). Kombucha tea is traditionally a sweetened black tea that is fermented with
a symbiotic culture of yeast and bacteria to produce a mild vinegar taste with an effervescent
finish (Marsh, O'sullivan, Hill, Ross,& Cotter, 2014; Watawana, Jayawardena, Gunawardhana,
& Waisundara, 2015). This tea has been brewed in China for over 2,000 years and has acted as a
functional beverage due to its ability to combat chronic illnesses such as CVD, cancer and type 2
diabetes (Marsh et al., 2014; Watawana et al., 2015).
There are many different techniques to produce brewed coffee with varying amounts of
antioxidants (Babova, Occhipinti, & Maffei, 2016; Lopez-Galilea, Peña, & Cid, 2007; Ludwig,
Bravo, Peña, & Cid, 2013; Yilmaz, Hacibekiroglu, & Kolak, 2014). These brewing techniques
can be generally characterized by brewing pressure, brewing process, extract volume, and solid
content (ParentI et al., 2014). The current brewing method that results in highest antioxidant
capacity when compared to other conventional brewing techniques is the espresso method,
obtained via percolation of hot water under pressure through compacted roasted ground coffee
(Illy & Viani, 2005; Lopez-Galilea et al., 2007; Ludwig et al., 2012). Another brewing technique
commonly used is cold brewing, which uses coarsely ground coffee mixed with cold water and
left in a refrigerator for at least 12 hours (Perratore, 2016). This novel form of brewing coffee
can lead to potentially higher extract of antioxidant levels.
53
Materials and Methods:
Subject Recruitment, Selection, and Training
The consumer acceptability study was submitted and accepted by the Institutional
Review Board (IRB) at California State University, Long Beach (CSULB). Consumer testing
was conducted in the sensory evaluation laboratory at the CSULB Department of Family and
Consumer Sciences (FCS) building. The sensory evaluation testing was performed under
controlled conditions—isolated booths, controlled lighting and temperature. Ninety untrained
subjects were recruited by flyers and advertisements (Appendix B). Subjects may mainly consist
of staff and students from CSULB. Subjects were required to complete a questionnaire that
requests demographic information (age, gender, ethnicity) along with shopping habits prior to the
testing (Appendix C). Subjects in this study were excluded if they: (1) have a food allergy to any
of the products tested, (2) do not consume Kombucha or coffee products used in the study for
dietary or cultural reasons, and (3) had any professional experience in sensory evaluation. The
subjects were free to withdraw from the study without any consequences. Subjects were required
to sign an informed consent form and were compensated for their participation in this study
(Appendix D). Consumer acceptance was determined using three tests: (1) Ranking Tests, (2) 9-
point Hedonic Scale, (3) Food Action Rating Scale (FACT) test.
Instrumentation and Procedure
Development of BubbLê Kombucha Coffee Prototype
Coffee Brewing Techniques
The brewing of coffee using cold methods were performed according Temple Coffee
Roasters. In preparation of the coffee brew, high quality coffee beans (donated from Temple
54
Coffee Roasters, Sacramento, CA, USA) were used. Each coffee brewing technique was
conducted in triplicates and stored in the refrigerator until analysis.
Cold Brewing
Five-hundred grams of coffee was coarsely grounded using a Baratza Encore 485 Coffee
Grinder set at the 27-grind setting (Figure 1). The ground coffee was immersed in 4000 mL of
cold water, then placed in a refrigerator set at 3.3°C (38°F) for 18 hours (Figure 2). The brewed
coffee was filtered from the coffee grounds with a metal mesh strainer placed in a Chemex
(Figure 3). The process was repeated 2 more times.
FIGURE 1. Encore 485 grinder set at 30 and coffee grounds. Photo courtesy of Linh Le. Copyright 2017.
55
FIGURE 2. Cold brew coffee before refrigeration. Photo courtesy of Linh Le. Copyright 2017.
FIGURE 3. Chemex with metal mesh strainer. Photo courtesy of Linh Le. Copyright 2017.
56
Fermented Coffee Formulation
The fermented coffee formulation was produced in similar conditions as, Marsh and
others (2014), with the exception of coffee being used in place of tea. A Kombucha cellulose
pellicle starter Kombucha culture was used. The coffee was brewed and weighed for
determination of sugar (10%). Fermentable sugar was determined by multiplying total brewed
coffee by 10% and divided in half for 1st and 2nd ferment. The sugar was dissolved in 500mL of
hot water and cooled then added to the brewed coffee in a sterile glass container (Ball® Mason
Jar). The Kombucha cellulose pellicle was added to the coffee solution (Figure 4). The container
was covered with a 100% cotton towel and an elastic band was fixed on. The coffee mixture and
Kombucha cellulose was placed in a dark space at room temperature (~23 °C) and fermented for
5 days. The 2nd half of sugar was dissolved in 500mL of hot water and cooled then added to the
fermented coffee to be bottled in airtight 16 oz bottles for second fermentation of 14 more days.
After the second fermentation the developed BubbLê product was refrigerated at 4°C until
sensory analysis is performed.
57
FIGURE 4. Kombucha fermentation. Photo courtesy of Linh Le. Copyright 2017. Evaluation of Consumer Preference and Acceptability of the Kombucha Coffee
The evaluation of consumer preference and acceptability of BubbLê Kombucha Coffee
prototype was conducted using the following sensory analysis tests: (1) A nine-point Hedonics
Preference test, (2) the Food Action Rating Scale (FACT) and a (3) Paired-Comparison test.
More specifically, acceptability, or likeability, was determined by the Hedonics and FACT test,
which identified overall acceptance of the product’s sensory characteristics. Preference of
BubbLê Kombucha Coffee versus market alternative was analyzed using a pair-comparison test,
which does not indicate an overall liking or dislike of the products. All sensory tests were
performed at the Family and Consumer Sciences (FCS) sensory evaluation laboratory at CSULB.
Water (20°C) and unsalted crackers were provided to participants at the beginning of each test to
cleanse their palates between samples during sensory evaluation of the prototype.
9-Point Hedonics Preference Test
Subjects were administered a 9-point hedonic scale for sensory evaluation where: (9 =
“like extremely”; 8 = “like very much”; 7 = “like moderately”; 6 = “like slightly”; 5 = “neither
58
like nor dislike”; 4 = “dislike slightly”; 3 = “dislike moderately”; 2 = “dislike very much”; 1 =
“dislike extremely”) to rate the prototype for attributes such as flavor, sweetness, tartness, aroma,
mouthfeel, and overall preference (Appendix E2). Panelists were provided with two randomly
coded samples of the fermented coffee prototype and a control sample i.e., commercial brand.
The samples were distributed in 2 oz. clear plastic cups. Samples will also be administered
randomly to avoid bias. Water and unsalted crackers were supplied to the panelists to cleanse
their palate between samples.
Food Action Rating Scale
The FACT test will measure the fermented coffee prototype for the incidences of drinking
measurement as described by Ramcharitar and others (2005). A 9-point scale were used and is as
follows: 9 = “I would drink this every opportunity I had”; 8 = “I would drink this very often”; 7
= “I would frequently drink this”; 6 = “I like this and would drink it now and then”; 5 = “I would
drink this if available but would not go out of my way”; 4 = “I do not like this but would drink
this on occasion”; 3 = “I would hardly ever drink this”; 2 = “I would drink this if there were no
other beverage choices”; 1 = “I would drink this only if forced”. Additionally, subjects were
asked how much they would be willing to pay for the product (Appendix E3).
Paired-Comparison Test
The consumer acceptability study was submitted and accepted by the Institutional
Review Board (IRB) at California State University, Long Beach (CSULB). Consumer testing
was conducted in the sensory evaluation laboratory at the CSULB Department of Family and
Consumer Sciences (FCS) building. The sensory evaluation testing was performed under
controlled conditions—isolated booths, controlled lighting and temperature. Ninety untrained
subjects were recruited by flyers and advertisements (Appendix B). Subjects may mainly consist
59
of staff and students from CSULB. Subjects were required to complete a questionnaire that
requests demographic information (age, gender, ethnicity) along with shopping habits prior to the
testing (Appendix C). Subjects in this study were excluded if they: (1) have a food allergy to any
of the products tested, (2) do not consume Kombucha or coffee products used in the study for
dietary or cultural reasons, and (3) had any professional experience in sensory evaluation. The
subjects were free to withdraw from the study without any consequences. Subjects were required
to sign an informed consent form and were compensated for their participation in this study
(Appendix D). Consumer acceptance was determined using three tests: (1) Ranking Tests, (2) 9-
point Hedonic Scale, (3) Food Action Rating Scale (FACT) test.
Data Analysis
Descriptive statistics, including frequencies, percentages, and variance, were calculated
for scorecard ratings. A paired t-test was used to compare means and standard deviations (SD)
for each of the sensory attribute of Hedonic rating and FACT scores. Overall statistical tests used
for acceptability the Kombucha Coffee prototype was tested via the International Business
Machine Statistical Package for Social Sciences (IBM SPSS) Statistics 22 for Windows. All
analysis tests were performed using a significance of at least p < 0.05.
Results and Discussion
(1) Nine-point Hedonics test
The market Kombucha Coffee, compared to the Kombucha Coffee prototype (BubbLê),
scored statistically significantly higher in flavor (6.84±1.82; 4.46±2.48; p<0.001), sweetness
(7.11±1.63; 4.65±2.33; p<0.001), tartness (6.27±1.77; 4.72±2.55; p<0.001), aroma (6.30±1.82;
5.55±2.59; p=0.018), mouthfeel (6.87±1.62; 5.36±2.64; p<0.001), and overall likeability
(6.90±1.76; 4.59±2.43; p<0.001) in the Hedonics evaluation (Table 1) respectively. On the
60
Hedonics scale from 1 to 9, the BubbLê Kombucha Coffee overall was rated 4.59±2.43 (dislike
very much to like moderately) for overall likeability, and the market Kombucha Coffee was rated
6.90±1.76 (neither like nor dislike to like very much).
It is noted that the highest scoring sensory evaluation for BubbLê Kombucha Coffee was
the aroma (5.55±2.59), which was shown in other studies to be the most important aspect of
coffee. Aromatic components are particularly important in coffee beverages due to it being the
main constituent of the sensory experience for coffee drinkers (Bhumiratana, Adhikari and
Chambers, 2011). Participants could have also been influenced by their own experiences and
expectations of what coffee should taste like versus what BubbLê Kombucha Coffee tastes like
for their scoring of the product (Kemp, Hollywood and Hort, 2009). Although this product was
developed with an aim to have more traditional coffee flavors, the process of fermentation
changed the flavor profile; however, findings from this research highlights the potential of
developing this product further with a focus on enhancing the other traditional attributes of
coffee such as flavor, tartness and sweetness.
(2) Food Action Rating Scale (FACT)
The frequency of consumption for the BubbLê Kombucha Coffee was significantly lower
(p<0.001) compared to the market alternative. On the FACT scale from 1 to 9, the average rating
for the BubbLê Kombucha Coffee was 3.62±2.29 (I would drink this only if forced, to, I like this
and would drink it now and then), while the market alternative was 5.42±1.96 (I would hardly
ever drink this, to, I would frequently drink this) (Table 1). The scores for the frequency of
drinking either product was 1 to 9.
Previous researchers have shown the likeability of a traditionally characterized cup of
coffee (Cliff and Green, 1994; Taylor and Roozen, 1996); however, the participants in this study
61
have shown that the hedonic qualities of BubbLê Kombucha Coffee was negatively affected with
the more traditional flavors when compared to a market alternative. Researchers have found that
the addition of cardamom (Amonum cardomum), a popular spice, to traditional brewed coffee,
was shown to increase the hedonic score for taste over traditional coffee without cardamom
(Febrianto, Rizki and Djumarti, 2015). In order to increase the frequency of consumption of
BubbLê Kombucha Coffee, further development of the product using spices such as cardamom
to enhance the coffee flavor will increase the likability of the product.
(3) Paired-Comparison test
The Paired-Comparison test showed that 80% of participants preferred the market
Kombucha Coffee and 20% the Kombucha Coffee prototype (Table 2). This test aligns with the
scores provided by other measures (i.e., Hedonics and FACT test). The market product scored
highest on sweetness whereas the prototype’s sweetness was second to the lowest score.
Considerations in further development of BubbLê Kombucha Coffee can include adjustment of
the sweetness level of the product to be sweeter like the market alternative.
In addition to sensory aspects of the study, 33% of participants “never” drinks coffee
ranging up to “once or twice a month” and 51% never tried Kombucha prior to the study,
showing that this could have led to possible bias in the results. The results were also similar to
previous researchers who found lower hedonics scores from participants when the taste of the
product was unfamiliar (Febrianto, et al., 2015). Future studies of this product can include, using
participants who have already tried Kombucha and enjoy drinking coffee.
Conclusion:
This study examined the consumer overall acceptability of a Kombucha Coffee
developed with traditional coffee characteristics compared to a market alternative without those
62
key characteristics. The findings of this study indicate that consumers preferred the market
alternative to the developed BubbLê Kombucha Coffee. It was also observed that the most
distinguished characteristic of coffee, aroma, scored highest for consumer acceptability of a more
coffee-like Kombucha. Development of another product incorporating key characteristics of
coffee may be more successful if the flavor were enhanced to taste more like coffee. For
example, one may try different spices such as, cardamom, or increase the amount of naturally
flavored extracts to enhance and compliment the flavor profile of coffee. Moreover, the use of
novel technologies and varying coffee extraction methods to extract coffee should be explored.
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doi:10.2337/dc08-2251 Tables: Table 1. Palatability ratings and overall acceptability of Kombucha Coffees
BubbLê Market P value Flavor (μ ± SD),
n=87 4.46±2.48 6.84±1.82 <0.001
Sweetness (μ ± SD), n=85
4.65±2.33 7.11±1.63 <0.001
Tartness (μ ± SD), n=82
4.72±2.55 6.27±1.77 <0.001
Aroma (μ ± SD), n=86
5.55±2.59 6.30±1.82 0.018
Mouthfeel (μ ± SD), n=86
5.36±2.64 6.87±1.62 <0.001
Overall (μ ± SD), n=87
4.59±2.43 6.90±1.76 <0.001
FACT* (μ ± SD), n=73
3.62±2.29 5.42±1.96 <0.001
Scale for all attributes: Range 9 = “like extremely” to 1 = “dislike extremely” (Peryam & Pilgrim, 1957). *FACT scale rating: Range 9 = “I would eat this every opportunity that I had” to 1 = “I would eat this only if forced” (Schutz, 1965). Table 2. Determination of Preference with Pair-Preference test
BubbLê n=18
Market n=72
n=90
20% 80% 100%
66
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